Question

A bank manager wishes to estimate the average waiting time for customers in line for tellers. A random sample of 50 times is measured and the average waiting time is 5.7 minutes. The population standard deviation of waiting time is 2 minutes. Which Excel function would be used to construct a confidence interval estimate?

a. NORM.INV
b. T.INV
c.INT
d.CONFIDENCE.NORM

Answer 1

d) CONFIDENCE.NORM

Explanation:

Given that a bank manager wishes to estimate the average waiting time for customers in line for tellers.

A random sample of 50 times is measured and the average waiting time is 5.7 minutes. n =50: mu = 5.7 and sigma = 2

To construct a confidence interval we use excel function as

d) CONFIDENCE.NORM

a) is wrong because this is to get normal x value

b ) is to get left tailed t inverse value

c) INT is to get the integer part of a decimal number

Option d is right